1. Field of the Invention
This invention relates to a process for producing a linear organotetrasiloxane with a low molecular weight which has a silanol radical at both ends thereof.
2. Description of the Prior Art
Heretofore, silanol-terminated, low molecular weight linear polysiloxanes have been produced by hydrolyzing a linear organotetrasiloxane having a chlorine atom at both ends thereof in a weakly alkaline aqueous solution.
There is also known a method of producing the above-mentioned polysiloxane by acetoxylating or alkoxylating the above-mentioned organochloropolysiloxane by use of acetic acid or alcohol and hydrolyzing the acetoxylated or alkoxylated compound.
The former method in which hydrolysis of an organochloropolysiloxane is carried out in an weakly alkaline aqueous solution, however, has a problem associated with instability of the silanol radicals to acid or alkali. The problem is that, during hydrolysis, a condensation reaction is caused by the alkali or by HCl arising from the hydrolysis, and, as a result, the formation of the intended organopolysiloxane is accompanied by the formation of organosiloxanes with higher molecular weights or cyclic polysiloxanes. It is very difficult to separate the intended linear organotetrasiloxane with a low molecular weight from the by-produced organopolysiloxanes.
In the latter method in which the intended compound is produced through acetoxylation or alkoxylation, on the other hand, acetoxy or alkoxy radicals are left in the product.